Viscosimeter



Patented Dec. 28, 1948 VISOOSIME'IEB Walter D. Lawslie, Seattle, Wasln, assignor, by mesne assignments, to Monsanto Chemical Company, Seattle, Wasla, a corporation of Delaware Application August 28, 1948, Serial No. 893,558

Claims. (CI. 73-59) The present invention relates to a wide range torsional viscosimeter adapted for directly indicating viscosity changes of a fluid as they occur in a chemical process so as to permit immediate application of control measures.

Narrow range torsional viscosimeters of the indirect or sampling type have long been used but they are unsatisfactory for controlling chemical processes where there is usually no time to withdraw and test samples in order to ascertain the need for making some change in the process.

'The operating principle of torsional viscosimeters is to suspend an element within a cup, containing the fluid to be measured, by means of a torsion wire attached to an external fixed support and then create a rotating movement in the fluid which tends to impart a twist to changes in a fluid. In the first place, it is not possible to rotate a large reaction vessel containing fluid. It is also impractical to rotate the external support for the immersion element.

Another difficulty is the irregular turlzoulonce within the mass of fluid created by the stirring devices necessary in most chemical processes. Further serious difficulty lies in the fact that any single torsion wire has a quite narrow range over which it can be twisted to give an accurate indication of viscosity and the changes to be determined in chemical processes are usually much wider than the range of any single ,wire.

On the other hand, control by the sampling of apparatus is too slow and inaccurate to be effective. During the time required to withdraw and test a sample, critical changes often occur in the main batch and the readings are also inaccurate because of temperature change during sampling. Difficulties of this character have My solution of this problem involves the new feature of extending the range of the usual single supporting torsion wire by a system of compounding so that small changes in viscosity can be accurately indicated by a light, easily twisted wire within a chamber which is rotated at constant speed and also performs the functions of continually supplying fresh material from the main body of the batch and damping out turbulence caused by stirring and circulating devices.

The invention is shown in illustrative embodi ment in the accompanying drawing in which Figure l is a view of the new apparatus partly in vertical section and partly in elevation.

Figure 2 shows in perspective and on an enlarged scale torque transfer and indicating devices which appear in Figure 1, and

Figure 3, is an enlarged section on line 3-'-'- of Figure l. I

1 Reference numeral it represents a tank con.- taining material ii, whose viscosity is to be tested, up to the level L, Figure 1. The tankha-s a top wall I2 on which is secured a frame it which supports a vertical tubular member M by means of Journal-thrust bearings It and It. Member it extends with running clearance throu h the top wall i2 and rigidly fixed to its lower end is a hollow head I! which comprises upper and? lower ,conicalwalls i8 and I! joined by a cylindrical wall 20 which is provided with a number of openings 3i. The bottom wall ID has a central opening 22 and, immediately above the head, member ii is provided with a plurality hitherto prevented a satisfactory solution of the problem so that the control of, many chemical processes has been left on a regrettably hit or miss basis with consequent variable quality of product.

The present invention solves this troublesome of side openings 23. Above the frame it member M has fixed thereto a pulley It engaged by a belt 25 driven from a pulley 26 on the armature an upright 28 engaging a triangular suspension member 88 to which is fixed a depending torsion member, here shown as a round wire 34. The wire extends freely downwardly through the constricted upper end of a tube t5 and its lower end is fixed to an 3 anchor member 38 which is seized in the lower end of tube 35. A nipple 81 is secured to the lower end of tube 85, as by threading thereon, and has fixed theretoa depending yoke 88 to the top of which are secured diametrically projecting arms 88 and 40 to whose undersides are fixed abutments I and 42 of which the latter is spaced substantially farther than the former from the axis of tube 85. Parallel horizontally projecting pim l3 and N on the yoke support a triangular suspension member 45 to which is fixed a depending torsion member here shown as a round wire 48 which is in alignment with wire 3. Wire 48 extends freely through the constricted upper end of a tubular vertical shaft portion 41 and is secured to an anchor member 48 seized in the lower end of portion 41. A shaft portion 418 is fixed to the lower end of portion 47, as by being threaded thereon, and has secured to its lower end a coaxial disc 88 which is symmetrically disposed in the head 1,! with considerable clearance all around.

Fixed to the upper end of portion 81 is a U- shaped member 8i including diametrical arms 82 and. and upwardly extending arms or abutment portions 88 and 88 whose upper ends, as most clearly shown in Figure 2, lightly bear against opposite sides of abutments II and 82.

Fixed on member 41 below member 52 is a graduated disc 56 with which cooperates a pointer 81 mounted on pedestal 28, Projecting from the pedestal is. an arm 88 in which is engaged the upper end of a tubular guide member 58, the upper end of member 59 beingconstricted to provide a running fit with shaft portion 41 and the lower end of member 58 having secured therein abushing 60 providing a running fit with shaft portion 49, the bushing having an out-turned flange wi a running fit with tubular member I.

The suspension members 33 and 48 fixedly hold the upper ends of wires 34 and 48 against rotation relative to the support 80 as to wire 34 and relative to yoke 88 as to wire 88, and with the lostmotion torque transmitting connection, constituted by the cooperating stop means, in the starting position illustrated, dial I8 is at zero position with respect to pointer 81. With the head end of tubular member I submerged below the side openings 23 and the tubular member being driven counter-clockwise, looking down, Figure 1, head ll operates as a centrifugal pump to draw the material II in through the side openings 23 and the bottom opening 22 and expel it through the peripheralopenings 2|. The paths of the material through the interior of the head are not radial .but are vortical due to the rotation of the head. The impingement of the dew on the faces of disc 50 causes'a drag on the latter so that the disc tends to be driven in the same direction as the head, that is, in the direction of the arrow, Figure 3. Inasmuch as the head is driven at constant speed, the torque efiect on disc 88 will be in direct twisting distortion to wire 3| through the coupling fitting 38. Therefore. as a result of the torque exerted on disc 88, wire 88 will be initially twisted without substantially disturbing the'position of yoke 38 as supported by wire 84.

' ,U-shaped member SI and dial 58 exactly reflect the turning of disc 58 as resisted by wire 48 and the two can turn nearly 360" relative to yoke 38 for the reason that abutment arm 58 travels in a circle inwardly of abutment 42 while abutment arm 58 travels in a circle outwardly of abutment ti, Consequently, after nearly 360 movement of disc 58 in the direction of the arrow, Figure 2,

abutment arms 54 and 85 will engage the opposite the described closing of the lost motionconnection and a secondary scale 82 maybe provided for reading after the connection has closed. The scale 82 may be arranged as a continuation of the scale 8| with the graduations appropriately closer together in accordance with the diflerence in torque resistance of the two wires. Obviously, a

further wire could be provided to take over after wire I4, and so on.

The described apparatus gives a continuous reading of greabaccuracy due to the circulation of material Ii through the head 19 and, obviously, the testing range of the apparatus can be made as wide as desired.

In Figure l it has not been attempted to go into great constructional detail since it is believed that any matters of design having to do with assembly problems are merely mechanical and unnecessary to enlarge upon. For example, it will be evident that the head I8 must be made in sections in order to be able to receive the disc- 80 whose diameter is substantially greater than the diameter of opening 22 or the inside of tubular member I. The invention is not limited to such matters of form and arrangement and the disclosure herein is intended to be merely illustrative of the invention as defined in the following claims,

I claim:

1. In a viscosimeter, a support, an upper torsion member fixed to and depending from said support, a lower torsion member in fixed connection with and depending from the lower end of said upper member, a rotatable member fixed to the lower end of said lower member, means for applying torque to said rotatable member in accordance with the viscosity of the material to be tested, said torsion members being unequally torque resistant so that one is twistable through the other, means operative before said twisting 7 range is exceeded for transferring the torque of said rotatable member from said one to said other torsion member, and indicating means driven from said rotatable member.

2. In a viscosimeter, a support, an upper torsion member fixed to and depending from said support, a lower torsion member in fixed connection with and depending from the lower end of said upper member, a rotatable member fixed to the lower end of said lower member, means for applying torque to said rotatable member in accordance with the viscosity of the material to be tested, the lower torsion member being less torque resistant than the upper so as to be twistable through a certain range by said rotatable member without imparting substantial twisting distortion to the upper torsion member, a lost-motion torque transmitting connection between said rotatable member and the lower end of said upper torsion member arranged to close before said range is exceeded whereby to transfer the torque of said rotatable member from of their cooperative abutments on the upper torsion member.

4. In a viscosimeter, a support, a relatively heavy wire fixed to and depending from said support, a fitting secured to the lower end of said heavy wire, a relatively light wire fixed to and depending from said fitting, a rotatable member fixed to the lower end of said light wire, said rotatable member being a rotary tubular memher, a hollow head fixed to one end of said tubular member, a rotatable shaft in said tubular mem-- her with a now space between the two, a disc fixed on said shaft within said head with flow clearance all around, said head having peripheral openings and having a central opening at its end opposite said tubular member and said tubular member having a side opening to said space whereby with the head end of the tubular member submerged at a level above said side opening in the material to be tested, rotation of the tubular member will cause the material to be drawn into said head through said side and central openings against the faces of said disc producing a torque on the latter and to be expelled through said peripheral openings, said light wire being twistable through a certain range by the torque produced on said rotatable member without imparting substantial twisting distortion to the heavy wire, a. lost-motion torque transmitting connection between said rotatable member and said fitting wherein the lost-motion connection comprises a pair of radial arms connected to the upper end of the lower torsion member, each of the radial arms having a cooperative abutment connected to the lower end of the upper'torsion member, said radial'arms being relatively swingable in difierent planes thereby permitting a relative swing of substantially 360 before engagement by the radial arms of their cooperative abutments on the uppertcrsion member whereby the torque of said rotatable member is transferred from the light to the heavy wire, and

indicating means driven from said rotatable member.

5. In a viscosimeter, a support, a relatively heavy wire fixed to and depending from said support, a fitting secured to the lower end of said heavy wire, a relatively light wire fixed to and depending from said fitting, a rotatable member fixed to the lower end of said light wire, means for applying torque to said rotatable member in accordance with the viscosity of the material to be tested, said light wire being twistable through a certain range by said rotatable member without imparting substantial twisting distortion to the heavy wire, a lost-motion torque transmitting connection between said rotatable member and said fitting arranged to close before said range is exceeded whereby to transfer the torque of said rotatable member from the light to the heavy wire, and indicating means driven from said rotatable member.

WALTER D. LAWSHE.

REFERENCES CITED The following, references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 2,203,132 Delamere June 4, 1940 Hurndall Dec. 15, 1942 

